Researchers from Skoltech, MIPT, the National Academy of Sciences of Belarus’ Institute of Bioorganic Chemistry (IBOCH NAS), and the Russian Academy of Sciences’ Institute of Biomedical Chemistry have studied the structures of ferredoxins from Mycobacterium tuberculosis and their complexes with interacting proteins. The study aims to discover new targets for anti-tuberculosis drug development by closely examining the structures of ferredoxins from the tuberculosis bacterium and their interactions with other proteins. In the fight against tuberculosis, these discoveries may represent a significant advance.
3Fe–4S Ferredoxins in M. tuberculosis
Ferredoxins are small proteins with iron and sulfur that are essential for many metabolic processes. However, the 3Fe-4S type of ferredoxin is the least studied of all ferredoxins, primarily because it requires anaerobic conditions. Until now, it was unclear how these ferredoxins’ structures interacted with those of their cytochrome P450 redox partners. However, thanks to the discovery of the structures of 3Fe-4S ferredoxins from Mycobacterium tuberculosis, both in their native form and in fusion with FdxE-CYP143, we now have a clearer picture.
Structural Diversity of 3Fe–4S Ferredoxins in M. tuberculosis
Mycobacterium tuberculosis, the bacterium that causes tuberculosis, has five ferredoxins in its genome. The researchers discovered that two of these 3Fe-4S ferredoxins are located close to genes that encode P450 cytochrome genes. These proteins are being researched as potential tuberculosis drug targets because they play a significant role in intracellular reactions. The proximity of these genes raises the possibility of an interaction between ferredoxins and cytochromes. Electrons from protein partners like ferredoxins are required for cytochromes to function properly.
To examine the structures of the individual ferredoxins, Fdx, CYP143, and their complex form, FdxE-CYP143, in greater detail, scientists used crystallography. The team identified the specific regions of the ferredoxins responsible for binding to other proteins and determined how electrons were transferred between them after closely examining the ferredoxins. The FdxE and CYP143 genes were found to be close to one another in the tuberculosis bacterium genome, which led the researchers to believe that they cooperate. The researchers examined their interactions with a technique known as surface plasmon resonance to determine whether this was, in fact, the case. The findings were unambiguous: these proteins have a solid bond, confirming the original theory.
Further analysis of the thermodynamic parameters has shown that electrostatic interactions and hydrogen bonds primarily govern the interaction between the partners. In simpler terms, this indicates that electrical charges and the shared use of hydrogen atoms are the leading causes of the forces that exist between partners.
The researchers’ investigation of the ferredoxin-cytochrome pair from mycobacteria produced some astonishing results. They used crystal structures to get a closer look at how the proteins interact with one another and were able to identify several hydrogen bonds and electrostatic contacts that help keep the complex together. The research team also looked at the cytochrome to determine precisely how much the interaction with ferredoxin affected it on its own. So what did they find out? However, they were able to pinpoint precisely which parts of the proteins were affected by the interaction.
It is necessary to crystallize proteins in order to determine their atomic structure more closely. Because the molecule may occasionally change during this process, it is crucial to verify that the conclusions from the crystal-based study hold true under realistic conditions to validate the reality of the findings. In addition, the researchers conducted some additional experiments to better understand the interactions between FdxE and CYP143 in a solution that mimics their naturally hostile environment. Researchers demonstrated how ferredoxins and P450 cytochromes interact using small-angle X-ray scattering. CYP143 and FdxE were used as examples.
The study’s findings show that, depending on the situation, specific ferredoxin genes connected to the CYPome (Cytochrome P450 complement) in bacteria play a crucial role in regulating the production of particular metabolites. But little was known about these systems until recently. The study findings provide insight into how these proteins work together in electron transfer complexes. There are important implications for developing new therapeutic strategies for tuberculosis treatment that can be drawn from the research.
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Dr. Tamanna Anwar is a Scientist and Co-founder of the Centre of Bioinformatics Research and Technology (CBIRT). She is a passionate bioinformatics scientist and a visionary entrepreneur. Dr. Tamanna has worked as a Young Scientist at Jawaharlal Nehru University, New Delhi. She has also worked as a Postdoctoral Fellow at the University of Saskatchewan, Canada. She has several scientific research publications in high-impact research journals. Her latest endeavor is the development of a platform that acts as a one-stop solution for all bioinformatics related information as well as developing a bioinformatics news portal to report cutting-edge bioinformatics breakthroughs.